The recovery of hydrocarbons from subterranean zones relies on the process of drilling wellbores. The process uses drilling equipment situated at surface with a drill string extending from the surface equipment to the formation or subterranean zone of interest. The drill string can extend thousands of feet or meters below the surface. The terminal end of the drill string includes a drill bit for drilling (or extending) the wellbore. In addition to this conventional drilling equipment, the system also relies on some sort of drilling fluid, in most cases a drilling “mud” which is pumped through the inside of the drill string, cools and lubricates the drill bit and then exits out of the drill bit and carries rock cuttings back to surface. The mud also helps control bottom hole pressure and prevent hydrocarbon influx from the formation into the wellbore which can potentially cause a blow out at surface.
Directional drilling is the process of steering a well away from vertical to intersect a target endpoint or follow a prescribed path. At the terminal end of the drill string is a bottom-hole-assembly (“BHA”) which comprises 1) a drill bit; 2) a steerable downhole mud motor of rotary steerable system; 3) sensors of survey equipment (Logging While Drilling (“LWD”) and/or Measurement-while-drilling (“MWD”)) to evaluate downhole conditions as well depth progresses; 4) equipment for telemetry of data to surface; and 5) other control mechanisms such as stabilizers or heavy weight drill collars. The BHA is conveyed into the wellbore by a metallic tubular.
As an example of a potential drilling activity, MWD equipment is used to provide downhole sensor and status information to surface in a near real-time mode while drilling. This information is used by the operator to make decisions about controlling and steering the well to optimize the drilling speed and trajectory based on numerous factors, including lease boundaries, locations of existing wells, formation properties, and hydrocarbon size and location. This can include making intentional deviations from an originally planned wellbore path as necessary based on the information gathered from the downhole sensors during the drilling process. The ability to obtain real time data during MWD allows for a relatively more economical and more efficient drilling operation.
In both directional and straight (or vertical) holes, the position of the BHA must be known with reasonable accuracy to ensure the correct well trajectory. While extending the wellbore, evaluation of physical properties such as pressure, temperature and the wellbore trajectory in three-dimensional space is important. Other borehole parameters that may also be assessed include, but are not limited to, fluid flow rate, resistivity, and BHA bit data such as weight on bit, torque on bit, etc.
In most downhole operations, it is often necessary to insert or introduce gauges, sensors or testing instrumentation into the borehole in order to obtain information of borehole parameters and conditions. Such parameters might include, but are not limited to, temperature, pressure, directional parameters, and gamma radiation. The electrical componentry of the various sensors and gauges used to obtain the information is mounted on or near circuit boards which are contained within an apparatus. The circuit boards may be referred or positionally favoured to one side of the carrier apparatus. The gauges are typically protected as they are imbedded in the wall, and hence completely housed within the apparatus.
In downhole MWD, the MWD tool surveys the well as it is drilled and information regarding which way the motor is oriented is relayed back to the operator on surface. A typical Directional and Inclination (D&I) sensor package consists of a series of accelerometers and magnetometers which respectively measure the inclination of the tool (for example vertical is 0° inclination and horizontal is 90° inclination) and the earth's magnetic field to determine azimuth. Generally, all MWD tools contain essentially the same D&I sensor package to survey the well bore but the data may be sent back to surface by various telemetry methods. Such telemetry methods include, but are not limited to, the use of hardwired drill pipe, acoustic telemetry, fibre optic cable, Mud Pulse (MP) Telemetry and Electromagnetic (EM) Telemetry. In some downhole drilling operations there may be more than one telemetry system used to provide a backup system in case one of the wellbore telemetry systems fails or is otherwise unable to function properly.
The sensors used in the MWD tools are usually located in an electronics probe or instrumentation assembly contained in a cylindrical cover or housing, located near the drill bit. The surface retrievable probe housing is subject to harsh downhole environments with increased temperature and pressure, excessive shock and vibration, as well as fluid harmonics which are created as drilling fluid passes by the probe. The electronics and sensors of the MWD tool can therefore be easily damaged.
Currently in industry, deployment downhole of the MWD tools requires considerable manual manipulation of the control systems for the downhole tool. One of the last steps prior to setting the tool into the drill collar is the downloading of the tool's instruction commands or configuration files for operation of the MWD tool. This is typically accomplished by opening up the probe housing and providing an electrical communication connection between the probe electrical components and a surface computer system through some sort of CANbus/USB connection. Once the information has been transferred to the surface computer, the probe housing is re-secured and the tool is placed in the collar. There is an element of human error that can occur in this last step, such as not properly sealing the probe, which can cause failure of the tool. Furthermore, safety concerns due to improper handling of the tool can also be an issue with manipulation of the probe at location.
Bluetooth, standardized as IEEE 802.15.1, is a wireless technology standard for exchanging data over short distances from fixed and mobile devices, creating personal area networks with high levels of security. Primarily designed for low power consumption and low-bandwidth using radio (broadcast) systems, Bluetooth replaces cable connections while maintaining high levels of security. Bluetooth provides a secure way to connect and exchange information between devices such as mobile phones, laptops, personal computers, Global Positioning System (GPS) receivers, digital cameras and other devices. Bluetooth technology operates in the unlicensed industrial, scientific and medical (ISM) band at 2.4 to 2.485 GHz, using a spread spectrum, frequency hopping, full-duplex signal at a nominal rate of 1600 hops/sec. Each channel has a bandwidth of 1 MHz. The useful range may vary depending on radio class used in the implementation. The range of Bluetooth technology is application specific. The Core Specification mandates a minimum range of 10 meters, but there is no set limit and manufacturers can tune their implementations to provide the range needed to support the use cases for their solutions. On a drill rig location, range could be from approximately one meter (class 3 radio) to industrial class 1 radios of 100 meters.